The purpose of this grant is to provide "core" research and administrative suppport to a Center for Research in Mental Retardation. The individual programs within the Center are primarily oriented to biochemical genetics and to nutrition in human development. Active research programs are established in inborn errors of metabolism with special reference to glutaric aciduria, to disorders of carbohydrate metabolism such as glycerol kinase deficiency, and in enzyme characterization in the lysosomal storage diseases. The nutrition programs are concerned with the role of trace metals, especially copper, zinc and chromium, and with undernutrition and environmental deprivation in a number of parameters of brain development. There are also active cytogenetic and genetic linkage studies in progress as well as a training program in mental retardation research.